It is well known that in certain situations, air containing pollutants or other undesirable constituents, such as dust or odors, must be conducted away from a working station or a particular zone to be treated or transported to another place where it can be released without harm or nuisance to persons in the area. Hooded collecting means located in a position to receive the contaminated air are well known and, in general, a number of specialized air handling systems have been proposed for this purpose as represented by the following U.S. Pat. Nos.: 92,623 to Maguire of July 13, 1869, 3,380,371 to Scheel of Apr. 30, 1968, 3,412,530 to Cardiff of Nov. 26, 1968, 3,618,509 to Nichols of Nov. 9, 1971, 3,745,991 to Cauthier et al. of July 17, 1973, and 3,818,817 to Nederman of June 25, 1974.